Do Auto MCUs Need Proprietary Flash?

MADISON, Wis. — Globalfoundries this week rolled out a 55-nm semiconductor manufacturing platform, specifically designed to meet the stringent needs of the automotive industry.

The foundry's new automotive platform supports the implementation of non-volatile memory (NVM) in MCUs and SoC designs. Globalfoundries is also making available, on the same 55-nm platform, SST's embedded flash technology -- based on the SST-Microchip SuperFlash split-gate design. This opens a licensing door to second- or third-tier automotive chip suppliers with no flash technology of their own.

Cerntainly, there are other foundries also offering SST technology on their automotive qualified platforms. But Globalfoundries believes it's the first to make it available on 55-nm.

But since the 90-nm process hit the automotive chip market (around 2010), tradition started to crumble: integrated device manufacturers (IDMs) began working with foundries. Colestock calls this "phase one."

During that period, IDMs transferred to foundries core process technology that had been developed in-house. But IDMs continued to work on proprietary embedded memory technologies, and kept them close to the vest.

Why proprietary NVM? Embedded MCUs used in automotive, embedded NVM -- which needs to hold data and code -- must be highly reliable. This is so critical that many automotive chip vendors believed that they had to differentiate their embedded MCUs from everyone else's.

In "phase-two" era, where the industry is in today, Colestock explained that IDMs no longer develop their process technology themselves. They have yielded to foundries. Moreover, IDMs today are more willing to work with their contracted foundries on their proprietary flash technologies. That model allows a foundry to fabricate a certain proprietary embedded flash technology, but only for their IDM customer, not for anyone else.

Colestock sees "phase three" as the destination.

Although still several years away, phase three will happen when foundries offer both the process technology and "industry-standard" embedded flash memory technology to automotive chip vendors, Colestock noted. "Certainly we are not there yet, and we may not get there any time soon," he added.

The industry standard NVM for automotive Indeed, it's hard to imagine automotive chip companies rallying around "industry-standard" embedded flash memory technology, at a time when practically every leading automotive chip company is armed with its own embedded flash.

As Jim Handy, director of Objective Analysis, told EE Times, "IDMs use a variety of technologies, from the SST-Microchip SuperFlash split-gate design, which is very popular, to Freescale's proprietary silicon nanocrystal flash which is only used in a few Freescale MCUs. One or two IDMs use MirrorBit technology from Spansion."

Alan Niebel, analyst at Web-Feet Research, added to the list a whole lot more. Other embedded NVM technologies he included are:

MONOS embedded flash pioneered by Renesas; SONOS embedded flash used by Cypress; emFeRAM by Fujitsu; Fujitsu's emFlash (Floating Gate) sold to Spansion; emMRAM (qualified for automotive) produced by Everspin; CBRAM (Conducting Bridge RAM) developed by Adesto and offered through Altis, with Panasonic producing their own emCBRAM (although CBRAM may not be qualified for automotive yet); emPCM developed by STMicroelectronics but is also not yet qualified for automotive; Samsung, Toshiba, Atmel, ST, and many others offering emFlash (Floating Gate).

Important in the automotive context is that car OEMs are looking for embedded memory that must be integrated into MCU-MPU. In other words, the memory cells are part of the silicon of another component (MCU/SoC), and aren't packaged as a standalone component.

I've actually been through this process myself, Junko. There are two factors at play (at least), one of which Betajet mentioned.

Initially, the automaker or other system designer wants to get something truly innovative out there. There's nothing available that can be used, which is partly why this new idea is innovative.

What's the designer going to do? Initiate an excrutiatingly painful standards development process? And wait maybe 10 years or more for everyone to agree? Of course not. So he rolls his own, so to speak. And of course, components for the automotive environment typically have to meet at least as stringent environmental specs as mil-spec, so it takes a long time for any commodity item to gain their trust. As well it should.

But there comes a time when continuing on the path of rolling your own gets to be more of a burden than raising up your head, looking around at what's available out there, and then jumping into the cold water. So, you gain by making use of the work of a lot of great minds outside your company, no doubt about that, but now you've become vulnerable to the whims of the makers of these commodity products. You're relying on product lines that you don't control and life cycles you don't control. And now you're hiring people whose main job is to keep up with the ever-changing industry techniques and standards, because you're having to plan ahead on this basis.

@chanj, I think AEC-Q100 standards are exactly set up to answer your questions. Flash memories used in the embedded MCU in cars do need to meet the stringent standards -- as you just described.

And you are absolutely right. Cars must last much longer than consumer products.

That said, what I found most fascinating during the interview with the Globalfoundries' executive was that automotive chips in the future need to clear not only the AEC-Q100 standards but also ISO 26262 safety functions.

How automotive chips will be certified to be compliant with ISO26262 -- in terms of functional safety -- has not been spelled out yet. But at the advent of chips catering to active ADAS, this is a new thing to watch out.

The environmental condition in a automotive is going to be different than that in the appliances or computer devices in your house. In addition, electronics product typically has a 3 to 5 years life cycle. If the FLASH is worn out and the capacity decreases, you will buy a new one. Automotives, on the other hands, stay in an uncertain enviroment. Some are in a hot weather. Some constantly stay in a snow weather. Engine temperature is high; so is everything around it. Dusty and greasy are unavoidable. More importantly, most consumers expect a car live for 10+ years. Can today FLASH last that long? I think a standard shall be defined to give consumer a more confident of the next generation vehicles (more electronics to assist mechanical).

I wonder if non-automotive companies will start using the 55nm flash for general mcu's(because they' don't have access to 65nm flash which only a few has). And once that shift happens i can see them developing mcu's for 40nm - which can be surely used for commodities , see lattice semi ice40 sub dollar fpga's .

Of course that depends on how spansion's super bus would be accepted but in general , the rule in this business is (integrate or be integrated).

Other areas that might fit 28nm automotive is robotics : complex designs, need for speed, low power and reliability.

My paraphrase is based on a quote about sausage and public policy that is attributed to Bismarck, but it's not clear how he said it or whether he even said it at all. Personally, I don't care who said it because it's such a great quote. The form I used as my prototype is: "People who like sausage or public policy should not watch either being made." A surprising number of things can be substituted for "public policy" :-)

But more on a serious note, I was actually motivated to look into this further, when the executive from Globalfoundries discussed the "phase three" where automotive MCUs @28-nm may start looking for the "industry standard" flash.

Junko Yoshida wrote: I am shocked [shocked!] to find out there are so many different proprietary technologies out there.

Anyone who has spent more than five minutes listening to technical people arguing fervently and at length about the kind of minutiae that go into making a standard understands quite clearly why there are so many proprietary technologies.

To paraphrase Otto von Bismarck, "People who like sausage or standards should not watch either being made."